Remote Notifier - This project sends notifications to a desktop computer when certain events happen on an Android device, such as the phone ringing, an SMS being received, or the battery running low. The notifications can be sent over Wifi, Bluetooth, or (in the future) USB.
It runs as a service on Android, consuming little resources while no events are happening, and the desktop application (which is initially available for Mac - Linux and Windows will follow) notifies the user about the event in some way (Growl on Mac, Gnome dbus notifications on Linux, System tray alert on Windows), including information such as the number that's calling.
This is useful for people (like the developer) who wear noise-cancelling headphones, keep their cell phone in their bags, or don't want to be interrupted to look at a vibrating cell phone in a meeting.